COVID-19 short-term forecasts Confirmed 2020-07-03 Latin American Countries


Disclaimer

  • Forecasts produced by Jennie Castle, Jurgen Doornik, and David Hendry, researchers at the University of Oxford. These are our forecasts, and should not be considered official forecasts from, or endorsed by, any of: University of Oxford, Oxford Martin School, Nuffield College, or Magdalen College.
  • These forecasts are short term time-series extrapolations of the data. They are not based on epidemiological modelling or simulations. The documentation that is provided is still in progress and not peer reviewed. All forecasts are uncertain: their success can only be determined afterwards. Many mitigation strategies are in place, which, if successful, invalidate our forecasts. An explanation of our methods is provided below.

Recent changes

[2020-03-24] Our forecasts are starting to overestimate in some cases. This was always expected to happen when the increase starts to slow down. Scenario forecasts that are based on what happened in China earlier this year, but only for Italy and Spain sofar.
[2020-03-26] Scenario forecasts that are based on what happened in China earlier this year, only for Italy.
[2020-03-31] Scenario forecasts, based on what happened in China earlier this year, are presented for several countries (line marked with x). Created more plausible 90% confidence bands (dotted line in same colour).
[2020-04-02] Now including more US States, based on New York Times data.
[2020-04-06] Added a post hoc estimate of the peak number of cases. This needs at least three confirmed observations (four for deaths) after the event. It is based on the averaged smooth trend, and can change later or be a local peak. It is marked with a vertical line with the date label, or a date with left arrow in the bottom left corner of the graph. This is backported to 2020-04-04.
[2020-04-08] Minor correction to peak estimates. Added table with scenario forecasts.
[2020-04-09] Added table with estimated peak dates (if happened) and dates to and since the peak. Note that this can be a local peak, and subsequent re-acceleration (or data revisions) can result in a new peak later.
[2020-04-10] Updated documentation with better description of short-term estimates and peak determination.
[2020-04-16] Added scenario forecasts to all graphs now. This would now be the preferred forecast for most.
This is the first time with a peak in confirmed UK cases (also for deaths, but this is uncertain because it is at the same date).
[2020-04-17] Bird and Nielsen look into nowcasting death counts in England.
[2020-04-24] A summary of our work on short-term COVID-19 forecasting appeared as a voxeu.
[2020-04-27] Our short-term COVID-19 forecasting paper is now available as Nuffield Economics Discussion Paper 2020-W06.
A small adjustment has been made to the scenario forecast methodology, and will be documented shortly.
[2020-04-29] See our blog entry at the International Institute of Forecasters.
US history of death counts revised in Johns Hopkins/CSSE data.
UK death counts have been revised to include the deaths in care homes. In the Johns Hopkins/CSSE data set, which we use, the entire history has been revised. So forecasts made up to 2020-04-29 cannot be compared to later outcomes. In the ECDC data set only the last observation has changed, causing a jump in the series.
[2020-05-06] The New York Times is in the process of redefining its US state data. Unfortunately, at the moment only the last observation has changed (e.g New York deaths jumped from 19645 on 2020-05-05 to 25956 a day later). This means the data is currently useless; however it does bring it close to the Johns Hopkins/CSSE count (25626 on 2020-05-06). The aggregate US count is based on JH/CSSE so unaffected. We now use Johns Hopkins/CSSE US state data, including all states with sufficient counts. So the new forecasts cannot be compared to those previously.
A minor change is that we show the graph without scenario forecast if no peak has been detected yet.
[2020-05-13] We now omit countries with fewer than 200 confirmed cases in the last week (25 for deaths).
The short-term paper has some small updates, including further comparisons with other models.
Data for Ecuador are not reliable enough for forecasting.
Switched to an improved version of scenario forecasting.
[2020-05-18] Minor fixes to the improved version of scenario forecasting, backported to 2020-05-13.
[2020-05-20] Problem with UK confirmed cases: negative daily count. This makes the forecasts temporarily unreliable.
Updated the second paper.
[2020-06-04] Data issues with confirmed cases for France.
Added an appendix to the short term paper with further forecast comparisons for European and Latin American countries.
Both Sweden and Iran have lost their peak in confirmed cases. For Sweden the previous peak was on 24 April (daily peak of 656 cases), for Iran it was on 31 March (peak of 3116). For Iran this looks like a second wave, with increasing daily counts for the last four weeks. For Sweden this is a sudden jump in confirmed cases in the last two days, compared to a fairly steady weekly pattern over the previous six weeks.
[2020-06-06] Removed Brazil from yesterday's forecasts (only; last observation 2020-06-05).
[2020-06-24] Research presentation on short-term COVID-19 forecasting on 26 June (14:00 UK time) at the Quarterly Forecasting Forum of the IIF UK Chapter.
[2020-06-29] Tables in April included the world, but not the world as we know it (double counting China and the US). So removed the world from those old tables.
Why short-term forecasts can be better than models for predicting how pandemics evolve just appeared at The Conversation.
Thursday 2 July webinar at the FGV EESP - São Paolo School of Economics. This starts at 16:00 UK time (UTC+01:00) and streamed here.
[2020-07-01] Modified the short-term model to allow for (slowly changing) seasonality. Many countries show clear seasonality after the initial period, likely caused by institutional factors regarding data collection. This seasonality was also getting in the way of peak detection. As a consequence estimates of the peak date may have changed for countries with strong seasonality.
Added forecasts of cumulative confirmed cases for lower tier local authorities of England. The data is available from 2020-07-02 including all tests (pillar one and two). Only authorities with more than 5 cases in the previous week are included.

Further information

  • We believe these forecasts fill a useful gap in the short run. They give an indication of what is likely to happen in the next few days, removing some aspect of surprise. Moreover, a noticeable drop in comparison to the extrapolations could be an indication that the implemented policies are having some impact. It is difficult to understand exponential growth. We hope that these forecasts may help to convince viewers to adhere to the policies implemented by their respective governments, and keep all arguments factual and measured.
  • We use the data repository for the 2019 Novel Coronavirus Visual Dashboard operated by the Johns Hopkins University Center for Systems Science and Engineering. This is updated daily, but we tend to update our forecasts only every other day.
    US state data as of 2020-03-28 is courtesy of the New York Times.
  • We can only provide forecasts of what is measured. If confirmed cases are an underestimate of actual cases, then our forecasts will also be underestimates. No other epidemiological data is used. Data definition and collection differs between countries and may change over time.
  • We will update the methodology as we learn what is happening in the next few days or weeks. Once the number of cases levels off, there is no need to provide these forecasts anymore.
  • Countries where the counts are very low or stable have been omitted.
  • The graphs have dates on the horizontal axis (yyyy-mm-dd) and cumulative counts on the vertical axis. They show
    1. bold dark grey line (with circles): observed counts (Johns Hopkins CSSE);
    2. many light grey lines (with open circles): forecasts using different model settings and starting up to four periods back;
    3. red line (with open circles): single forecasts path using default model settings;
    4. black line (with crosses): average of all forecasts, recentered on the last observation;
    5. thin green lines: some indication of uncertainty around the red forecasts, but we do not know how reliable that is.
    Both the red line forecasts and the black lines are also given in the tables above. These forecasts differ, we are currently inclined to use the average forecasts.
  • The forecasts are constructed as follows:
    1. An overall `trend' is extracted by taking a window of the data at a time. In each window we draw `straight lines' which are selected using an automatic econometric procedure (`machine learning'). All straight lines are collected and averaged, giving the trend.
    2. Forecasts are made using the estimated trend, but we note that this must be done carefully, because simply extrapolating the flexible insample trend would lead to wildly fluctuating forecast. We use the `Cardt' method, which has been found to work well in other settings.
    3. Residuals from the trend are also forecast, and combined with trend forecasts into an overall forecast.
  • Scenario forecasts are constructed very differently: smooth versions of the Chinese experience are matched at different lag lengths with the path of each country. This probably works best from the peak, or the slowdown just before (but we include it for the UK nonetheless).
  • The forecast evaluation shows past forecasts, together with the outcomes (in the grey line with circles).
  • EU-BS is Estonia, Latvia, and Lithuania together.
  • This paper describes the methodology and gives further references. Also available as Nuffield Economics Discussion Paper 2020-W06. Still preliminary is the documentation of the medium term forecasts.

Confirmed count average forecast Latin America (bold black line in graphs) 2020-07-04 to 2020-07-10

DateArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaParaguayPeruVenezuela
2020-07-03 72786 36818 1539081 288089 106392 4311 35148 60657 7267 21293 6230 22116 245251 2519 35995 2349 295599 6537
2020-07-04 75910 38230 1591000 292400 111200 4415 36210 60850 7541 21700 6280 23210 252300 2543 36750 2434 298100 6830
2020-07-05 79370 39740 1642000 295700 116900 4581 37350 61230 7835 22510 6352 24360 260500 2564 37770 2526 301300 7105
2020-07-06 83000 41310 1693000 299200 121600 4796 38380 61720 8141 23450 6429 25540 268600 2581 38740 2596 304500 7406
2020-07-07 86790 42990 1764000 302500 126700 5018 39530 62330 8464 24450 6508 26760 278300 2862 39640 2662 307700 7733
2020-07-08 90760 44740 1841000 305800 131800 5250 40760 63000 8804 25510 6590 28070 288400 2862 40550 2734 310900 8045
2020-07-09 94910 46590 1920000 309200 137700 5492 41970 63720 9143 26600 6673 29450 299600 2881 41520 2820 314200 8371
2020-07-10 99250 48590 2017000 312300 144300 5744 43210 64440 9496 27720 6764 30890 310600 2904 42570 2942 317500 8708

Confirmed count forecast Latin America (bold red line in graphs) 2020-07-04 to 2020-07-10

DateArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaParaguayPeruVenezuela
2020-07-03 72786 36818 1539081 288089 106392 4311 35148 60657 7267 21293 6230 22116 245251 2519 35995 2349 295599 6537
2020-07-04 75690 38410 1596000 307000 111900 4507 36250 61310 7536 21880 6316 23790 254000 2665 36800 2349 299900 6857
2020-07-05 78730 40070 1639000 314200 116900 4701 37400 61960 7816 22530 6400 25110 263100 2712 37610 2349 303800 7114
2020-07-06 81860 41780 1680000 320600 122000 4904 38570 62620 8104 23230 6486 26170 272500 2761 38410 2349 307800 7440
2020-07-07 85140 43570 1742000 326000 127400 5105 39800 63250 8402 23950 6570 27240 282400 3094 39210 2349 311600 7777
2020-07-08 88550 45430 1810000 331100 133000 5313 41070 63880 8712 24710 6656 28450 292600 3097 40020 2349 315500 8131
2020-07-09 92090 47380 1880000 336200 138900 5530 42380 64520 9034 25490 6741 29780 303200 3141 40840 2349 319300 8454
2020-07-10 95790 49400 1969000 338500 145000 5754 43730 65160 9367 26290 6827 31150 314300 3141 41660 2349 323200 8778

Confirmed count scenario forecast (bold purple line in graphs) 2020-07-04 to 2020-07-12

DateArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaParaguayPeruVenezuela
2020-07-03 72786 36818 1539081 288089 106392 4311 35148 60657 7267 21293 6230 22116 245251 2519 35995 2349 295599 6537
2020-07-04 75530 38090 1571000 291000 110900 4430 35860 60860 7506 21660 6290 23110 250300 2576 37010 2422 298200 6742
2020-07-05 77770 39040 1601000 295200 113800 4581 36640 61310 7740 22290 6342 23940 254500 2611 37780 2504 300900 6912
2020-07-06 79740 39870 1620000 296900 116400 4773 37070 62160 7930 23050 6390 24870 257700 2652 38320 2589 303200 7087
2020-07-07 81540 40530 1648000 297800 120000 4952 37850 62710 8104 23610 6431 25740 261400 2681 39000 2713 304900 7262
2020-07-08 82970 41090 1667000 298800 122400 5062 38340 63090 8271 24200 6461 26470 263800 2705 39410 2788 306600 7386
2020-07-09 85130 41470 1687000 299800 124600 5195 38880 63240 8408 24750 6496 27200 267800 2725 39970 2903 307800 7453
2020-07-10 86430 41990 1709000 300600 127200 5366 39430 63280 8558 25270 6524 27840 271600 2746 40510 3005 309700 7543
2020-07-11 87710 42580 1733000 301400 130000 5474 39970 63420 8698 25840 6555 28580 274400 2760 41070 3106 310900 7626
2020-07-12 89300 43250 1755000 302500 132500 5605 40370 63550 8828 26300 6578 29200 277200 2775 41640 3226 312100 7723

Peak increase in estimated trend of Confirmed in Latin America 2020-07-03

ArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaParaguayPeruVenezuela
Peak date -- -- --06-17 -- -- --04-24 -- --06-03 -- --05-26 --06-2805-30 --
Peak daily increment 31850 7778 175 184 142 5882
Days from 100 to peak 93 38 28 7 84 72
Days from peak/2 to peak 48 18 30 8 88 53
Last total 72786 36818 1539081 288089 106392 4311 35148 60657 7267 21293 6230 22116 245251 2519 35995 2349 295599 6537
Last daily increment 2845 1290 42223 3548 4131 288 951 1189 267 1221 129 996 6740 0 758 46 3595 264
Last week 15042 6142 225414 20323 21732 1332 4529 6083 1540 4896 453 5109 32449 349 5337 407 19610 1407
Days since peak 16 70 30 38 5 34

Initial visual evaluation of forecasts of Confirmed